The field of the invention pertains to electric devices to open and close draperies or curtains, and in particular, to devices that automatically control the position of the draperies or curtains in response to light or heat.
A light actuated electric drapery drive is disclosed in U.S. Pat. No. 4,471,275 wherein the circuit provides overload protection in addition to providing opening and closing of the draperies by manual switches or the light sensor. The light sensor actuates the circuit to operate the drive motor upon sufficient lighting level.
U.S. Pat. No. 3,675,023 discloses combined heat and light sensors for mounting atop a building. The combined heat and light sensors are mounted for electro-mechanically driven movement to follow the sun during the day. In response to the heat and light striking the sensors with changing levels and direction throughout the day, the sensors control the opening and closing of draperies or Venetian blinds progressively about the building as the sun progresses about the building.
Of more general interest is U.S. Pat. No. 3,529,214 which discloses light responsive systems to automatically control street lamps. The systems include means in the circuit to ignore sudden flashes of light so that the street lamps will not be extinguished in response to a sudden and momentary flash of light.